Spelling fixes e to i.

tests/lib_strong/html/debugger_test.dart

 /// Debugger custom formatter tests.
 /// If the tests fail, paste the expected output into the [expectedGolden]
 /// string literal in this file and audit the diff to ensure changes are
 /// expected.
 ///
 /// Currently only DDC supports debugging objects with custom formatters
 /// but it is reasonable to add support to Dart2JS in the future.
 @JS()
 library debugger_test;
 
@@ skipping 284 matching lines @@
     }
     addFormatterGoldens('StackTrace', stack);
     test('hasBody', () {
       expect(_devtoolsFormatter.hasBody(stack, null), isTrue);
     });
   });
 
   group('Class formatting', () {
     addNestedFormatterGoldens('TestClass', new TestClass(17));
     addNestedFormatterGoldens('MouseEvent', new MouseEvent("click"));
-    // This is a good class to test as it has statics and a deep inheritance heirarchy
+    // This is a good class to test as it has statics and a deep inheritance hierarchy
     addNestedFormatterGoldens('HttpRequest', new HttpRequest());
   });
 
   group('Generics formatting', () {
     addNestedFormatterGoldens(
         'TestGenericClass', new TestGenericClass<int, List>(42));
     addNestedFormatterGoldens(
         'TestGenericClassJSInterop',
         new TestGenericClass<ExampleJSClass<String>, int>(
             new ExampleJSClass("Hello")));
@@ skipping 32 matching lines @@
         if (result) {
           print("Copy to clipboard successful");
         } else {
           print("Copy to clipboard failed");
         }
       });
     }
     expect(actualStr == golden, isTrue);
   });
 }